How can I reduce the number of queries Doctrine is performing?

Question

I'm building a product management tool where the product can have an arbitrary number of attributes , documents , features , images , videos as well as a single type , brand , and category . There are a few other related tables, but this is enough to demonstrate the problem.

There's a Model class called ProductModel that contains a method like this (reduced for clarity):

  public function loadValues() {
    //Product entity data
    $this->id = $this->entity->getId();
    $this->slug = $this->entity->getSlug();

    // One of each of these
    $this->loadType();
    $this->loadBrand();
    $this->loadCategory();

    // Arbitrary number of each of these
    $this->loadAttributes();
    $this->loadDocuments();
    $this->loadFeatures();
    $this->loadImages();
    $this->loadVideos();
    ...
  }

Each of the load methods does some boiler plate that eventually executes this method:

  public function loadEntitiesByProductId($productId=0) {

    // Get all the entities of this type that are associated with the product.
    $entities = $this->entityManager
      ->getRepository($this->entityName)
      ->findByProduct($productId);

    $instances = array();

    // Create a Model for each entity and load the data.
    foreach ($entities as $entity) {
      $id = $entity->getId();
      $instances[$id] = new $this->childClass();
      $instances[$id]->entity = $entity;
      $instances[$id]->loadValues();
    }

    return $instances;

  }

This is OK for cases where the related entity is a single table, but usually it's a mapper. In those cases, I get all the mapper entities in the first query then I have to query for the related entity within the loadValues() method (via Doctrine's get<Entity>() method). The result of this process is a huge number of queries (often >100). I need to get rid of the extraneous queries, but I'd like to do so without losing the idioms I'm using across my data models.

Is there a way to get the entityManager to do a better job at using joins to group these queries?

Answer 1

There were a couple problems with my previous approach:

First, I was getting the entities from the repository instead of loading them from the existing entity:

$entities = $this->entityManager
  ->getRepository($this->entityName)
  ->findByProduct($productId);

Better is:

$method = $this->deriveGetMethod($this->entityName);
$entities = $productEntity->$method()

Second, I was retrieving the product entity using $this->entityManager->getRespository... which works fine for loading small data sets (a single table or one or two relations), but there's no way to get the repository's findBy methods to load relations in a single query. The solution is to use the queryBuilder.

$qb = $this->entityManger->createQueryBuilder();
$query = $this->select('product',/*related tables*/)->/*joins etc.*/
$productEntity = $query->getSingleResult();